1. Field of the Invention
The present invention relates to a sealing structure for circulating each of a fuel gas, an oxidizing agent gas, a cooling medium and the like by an independent flow path, in a fuel cell.
2. Description of the Conventional Art
A fuel cell is provided with a sealing structure for circulating each of a fuel gas, an oxidizing agent gas, a cooling medium and the like by an independent flow path. FIG. 11 is a partly cross sectional view showing a fuel cell sealing structure in accordance with a prior art in a separated state, and FIG. 12 is a partly cross sectional view showing the same in a laminated state.
In these FIG. 11 and FIG. 12, reference numeral 110 denotes a power generating body obtained by laminating and integrating gas diffusion layers (GDL) 112 and 113 each of which is constructed by a porous body in both sides in a thickness direction of a membrane electrode assembly (MEA) 111 which is constructed by an electrolyte membrane and catalyst electrode layers provided in both surfaces thereof. Further, separators 120 and 130 each of which is constructed by a carbon or a conductive metal are laminated in both sides in a thickness direction of the power generating body 110, whereby a fuel battery cell 100 is constructed.
In each of the fuel battery cells 100, an outer peripheral portion of the membrane electrode assembly 111 in the power generating body 110 is pinched between a sealing protrusion 121 for an anode which is integrally formed in one separator 120 by a rubber-like elastic material (a rubber or a synthetic resin material having a rubber-like elasticity), and a sealing protrusion 131 for a cathode which is integrally formed in another separator 130 by the rubber-like elastic material.
Further, a fuel gas flow path 100a is defined by the sealing protrusion 121 for the anode between one catalyst electrode layer (an anode) in the membrane electrode assembly 111 and the one separator 120 which is opposed thereto, and an oxidizing agent gas flow path 100b is defined by the sealing protrusion 131 for the cathode between another catalyst electrode layer (a cathode) in the membrane electrode assembly 111 and the another separator 130 which is opposed thereto. Further, a sealing protrusion 122 for a cooling medium is integrally formed by the rubber-like elastic material on a surface which is opposed to the sealing protrusion 121 for the anode in the one separator 120, and a cooling medium flow path 100c is defined by the sealing protrusion 122 for the cooling medium between the separators 120 and 130 of the adjacent fuel battery cells 100 and 100.
In other words, this kind of fuel cell is structured such that a fuel gas (a hydrogen) circulating in the fuel gas flow path 100a is fed to the anode side of the membrane electrode assembly 111 via the gas diffusion layer 112, an oxidizing agent gas (an air) circulating in the oxidizing agent gas flow path 100b is fed to the cathode side of the membrane electrode assembly 111 via the gas diffusion layer 113, and an electric power is generated on the basis of a reverse reaction to an electrolytic process of a water, that is, a reaction for creating the water from hydrogen and oxygen, in each of the fuel battery cells 100. Further, an electromotive force by each of the fuel battery cells 100 is low, however, a necessary electromotive force can be obtained by laminating a lot of fuel battery cells 100 so as to connect electrically in series (refer, for example, to Japanese Unexamined Patent Publication No. 2005-222708).
However, in accordance with the conventional fuel cell sealing structure, it is necessary to integrally form the sealing protrusion 121 for the anode and the sealing protrusion 122 for the cooling medium in the one separator 120, and integrally form the sealing protrusion 131 for the cathode in the another separator 130.
Further, if the separators 120 and 130 become liable to be deformed by being thinned, end portions of the separators 120 and 130 in both sides of the power generating body 110 in the fuel battery cell 100 come into contact with each other so as to be electrically short circuited, and there is a risk that a power generating efficiency is lowered.